Question

define and drive law of conservation of energy

Answer 1

Energy can neither be created nor destroyed. It can be only converted from one form to another. This is known has the law of conservation of energy.

Answer 2

$\huge{HEY!!}$
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⭕This law states that energy can neither be created nor destroyed. It can only be converted from one form to another.

⭕Suppose an object of mass m Falls freely from a height h.

⭕At the start, the potential energy is mgh and kinetic energy is zero. The kinetic energy is zero because its velocity is zero. The total energy of the object is mgh.

⭕As it fall, its potential energy will change into kinetic energy. 

⭕If V is the velocity of the object at a given instant, the kinetic energy would be 1/2 mv^2.

⭕As the fall continuous, potential energy would decrease while the kinetic energy would increase.

⭕When the object is about to reach the ground h = 0 and V will be the highest, the kinetic energy would be largest and the potential energy will be the least.

⭕However, the sum of the potential energy and kinetic energy of the object would be the same at all the points.

⭕Potential energy + Kinetic energy = Constant
mgh + 1/2mv^2 = constant. 

⭕The sum of kinetic energy and potential energy of an object is called the total mechanical energy.